Quaternary Germanides RE₃TRh₄Ge₄ (RE = Ce, Pr, Nd; T = Nb, Ta) – A New Coloring Variant of the Aristotype AlB₂

Abstract

Abstract. The quaternary germanides RE 3 TRh 4 Ge 4 (RE = Ce, Pr, Nd; T = Nb, Ta) were synthesized from the elements by arc-melting and subsequent annealing in a muffle furnace. The structure of Ce 3 TaRh 4 Ge 4 was refined from single-crystal X-ray diffractometer data: new type, Pbam, a = 719.9(2), b = 1495.0(3), c = 431.61(8), wR 2 = 0.0678, 1004 F 2 values, and 40 variables. Isotypy of the remaining phases was evident from X-ray powder patterns. Ce 3 TaRh 4 Ge 4 is a new superstructure variant of the aristotype AlB 2 with an ordering of cerium and tantalum on the aluminum site, whereas the honey-comb network is built up by a 1:1 ordering of rhodium and germanium. This crystal-chemical relationship is discussed based on a group-subgroup scheme. The distinctly different size of tantalum and cerium leads to a pronounced puckering of the [Rh 4 Ge 4 ] network, which shows the shortest interatomic distances (253-271 pm Rh-Ge) within the

Magnetic and Transport Properties of a New Kondo-Lattice Compound Ce3NbRh4Ge4

“…These values agree with those reported in the ref. 4 within the experimental precision. We tried to synthesize a nonmagnetic counterpart "La 3 NbRh 4 Ge 4 " by the same procedure, but no traces of such compound were found in a X-ray diffraction pattern.…”

“…We tried to synthesize a nonmagnetic counterpart "La 3 NbRh 4 Ge 4 " by the same procedure, but no traces of such compound were found in a X-ray diffraction pattern. In fact, the existence of RE 3 NbRh 4 Ge 4 has been reported only for RE = Ce, Pr, and Nd [4]. The magnetization M(T, H) was measured using a superconducting quantum interference device magnetometer (Quantum Design, MPMS) as functions of the temperature T and magnetic field H between 1.8 and 300 K up to 5 T. The electrical resistivity (T) was measured with a dc four-probe method between 0.4 and 294 K in a laboratory-built 3 He cryostat.…”

“…Figure 1(a) shows the chemical unit cell of Ce 3 NbRh 4 Ge 4 . This cell is characterized by the existence of two crystallographically independent Ce sites (2c and 4h sites for Ce1 and Ce2, respectively) and a honey-comb like network of fully-ordered Rh 3 Ge 3 hexagons [4]. In the present study, we report on the results of magnetization, electrical resistivity, ac magnetic susceptibility, and specific-heat measurements of Ce 3 NbRh 4 Ge 4 .…”

“…Subsequently, we have searched for new FM compounds with quantum criticallity and have focused on a new compound Ce 3 NbRh 4 Ge 4 . This compound has been synthesized for the first time by Hoffmann et al [4] They have reported that this compound crystallizes with a new type of orthorhombic structure (space group Pbam, D 2h 9 , No. 55) [4].…”

“…This compound has been synthesized for the first time by Hoffmann et al [4] They have reported that this compound crystallizes with a new type of orthorhombic structure (space group Pbam, D 2h 9 , No. 55) [4]. Figure 1(a) shows the chemical unit cell of Ce 3 NbRh 4 Ge 4 .…”